The invention relates generally to equipment and methods for installing and removing stator bars to and from stator core slots in rotating electrical equipment for initial installation, maintenance and repair.
Certain rotating electrical equipment, for example a power generator, has stator bars. Stator bars comprise large electrical conductors that are capable of carrying large amounts of electrical power within the electrical equipment. Stator bars are assembled in the stator core slots and joined at the ends to form coils and connected in the proper phase belts by bus rings. Stator bars must be installed during initial assembly of the electrical devices or may need to be removed and replaced due to damage or maintenance to the stator bar or to other internal components of the electrical devices. In order to access the stator bars, the rotor must be removed to expose the space within the inner periphery of the stator core.
If the stator bar is removed for repair or replacement, it is manually carried from its slot in the stator core to a repair area and carried back to the core when the repair or replacement is completed. When initially installed or replaced, the heavy and unwieldy stator bar must be transported from a staging area for insertion into a slot within the stator core. Once the bar is inside the core, it is manually lifted and lowered to a correct slot and then inserted and wedged. Manually moving the unwieldy and heavy bars requires manpower and time and involves a safety hazard. The methods employed today require between 4 and 8 worker crew to lift and carry the bars, makeshift equipment for movement and positioning, and physically intensive manual positioning and supporting the stator bars within the stator core. Manual lifting of heavy stator bars into specific slots around the full inner radius of the stator core is an awkward operation, exposing the workers to possible injury. Current practice employs manual labor with a makeshift assortment of equipment to position and support the bars within the slots until the bar can be retained in place.
Further, errors when manual positioning of the heavy stator bars can result in dropping or unintended contact between the stator bars and the core resulting in damage to the stator bar or the core
Additionally, the stator core is a cramped space. Existing support equipment to assist in positioning and insertion of the stator bars must be set up to service slots in specific quadrants of the stator core and then taken down and reassembled to service the different quadrants of the stator core.
Accordingly, there is a need to provide an apparatus for and to improve the method of transporting and manipulating a stator bar to position it to a correct slot so that the stator bar can be inserted and wedged into position. There is also a need for a device that can be assembled once and which will provide for inserting stator bars around the full 360 degree inner surface of the stator core.